The byproduct of the sake-making process may not be internationally known, but it's an important ingredient in Japan. This byproduct is sake kasu, also known as the lees left behind after the liquid is expressed from fermented rice. These solids are separated during the pressing stage of sake production, but just because sake kasu is technically a leftover, it should never go to waste!There are many culinary uses for sake kasu. Many breweries vacuum-pack it and sell it frozen to supermarkets throughout Japan, allowing people to buy it year-round. However, fresh sake kasu that comes straight from sake makers is the best, and full of complex flavors. Sake Kasu is packed with umami enhancing compounds, making it ideal for cooking, but its characteristics will vary depending on the type of sake it comes from. In Japan, this unique ingredient is used to add flavor to many different dishes, including soups and marinades.Aside from adding flavor and complexity to food, sake kasu is very nutritious and full of fiber, amino acids, and vitamins. And on the beverage side, it can be used to make amazake (a traditional, sweet, low- or non-alcoholic drink) or distilled to make shochu.